1. Field of the Invention
This invention relates to drive assemblies for valves and, more particularly, to offset drive assemblies for coupling nutating motors to valve assemblies.
2. Prior Art Relating to the Disclosure
A nutating motor provides low-speed, high torque drive capabilities for driving an operator for fluid control valves and the like. Valves for pipes having diameters of several inches or more weigh from 50 to 500 pounds, and the operators used with such valves weigh over 100 pounds. Access to the valve stem of a valve driven by prior art motor-driven operators is difficult, often requiring the heavy operator to be unbolted and removed. A handwheel is then connected to the valve stem for manually operating the valve. For maintenance this is a time-consuming cumbersome procedure; and for emergency situations, this is an unacceptable procedure. Prior motor driven valve operators are also not readily adaptable to provide different speeds for different applications using a fixed-speed drive assemblies. It is often necessary to provide each valve size with an operator tailored for use with that valve size resulting in large inventories and lack of standardization.